Today there exist multiple types of wireless wide-area network types. These include Second Generation networks (CDMA, TDMA and GSM) that support Circuit-Switched (CS) voice and data services as well as Third Generation Networks (cdma2000, UMTS) that support Circuit-Switched (CS) voice and Packet-Switched (PS) data services. Evolution of Second Generation networks may also support CS and PS data services, albeit over air interface technologies and networks that are not as optimized as those in Third Generation networks.
Each type of Second Generation (2G) and Third Generation (3G) network, consist of Radio Access Networks (RAN) interconnecting multiple type of UE (user equipment) (e.g., handsets) to a CS or PS Core Network (CN), over specific air interface technologies unique to the network type. A cellular CS CN consists of a variety of functional elements, including, but not limited to, one or more instance of a Mobile Switching Centers (MSC) and Home/Visiting Location Register (H/VLR). Signaling within the CS CN is based on an ANSI-41 (CDMA, TDMA, cdma2000,) or MAP (GSM, UMTS) using interfaces based on Signaling System No. 7. A cellular PS CN consists of packet data nodes such as a GPRS Support Node (GSN) or Packet Data Serving Node (PDSN), for GSM/TDMA/UMTS and CDMA, respectively. These elements in turn interface to external packet data networks (PDNs), including those that comprise the global Internet.
In Second and Third Generation Networks, feature application servers (ASs) interface with the CS, or CS and PS CN, respectively to provide client-server based services for UE. For example, a Short Message Service Center (SMS-C) provides short message services to/from UE located within or across CNs owned by different operators.
The IP Multimedia Subsystem (IMS) refers to a core network that supports multimedia services over future evolution of 3G networks, where there exists only a single CN supporting convergent voice and data services, i.e., multimedia services. The multimedia services are based on Voice over IP protocols for signaling and media transport. An IMS CN consists of a variety of standardized functional elements, including, but not limited to, one or more instances of a Call Session Control Function (CSCF), Breakout Gateway Control Function (BGCF), Media Gateway Control Function (MGCF), Home Subscriber Server (HSS), Media Gateways (MGW), and Application Server (AS). Signaling within the IMS CN is based on the Session Initiation Protocol (SIP) using any interface compatible with the Internet Protocol (IP). Herein, IMS is defined as the system specified by the Third Generation Partnership Project (3GPP) and Third Generation Partnership Project 2 (3PP2).
In a cellular context, the IMS can be deployed in conjunction with a Third Generation RAN. The IMS can also interwork with external networks, such as today's wired telephony network (PSTN) or external PDNs. However, it can also be deployed in conjunction with other RANs (Wi-Fi, Wi-MAX, etc.) and wireline access networks (e.g., ADSL, Cable, Fiber, etc.).
In the IMS CN, a variety of feature application servers (ASs) may exist to client-server based services for particular UE configurations. A primary difference between non-IMS and IMS based networks is that, in the latter case, application servers increasingly realize multimedia based services and increasingly interface with the PS CN (the IMS CN), unless they expressly designed to interface between PS and legacy CS CNs.
Wireless UE may consist of distinct mobile terminals (MT) and terminal equipment (TE)—such as a Personal Computer (PC) containing a wireless adapter card compatible with a RAN type—or consist of an integrated MT and TE—such as a mobile phone (handset). Of course, hybrid types of UE are also possible, differing in the type of MT (e.g., the PC can take the form of a laptop PC or a Personal Digital Assistant (PDA)), or level of integration between between MT and TE components (e.g., PDA phone).
In today's varied networks, the entity that keeps track of a subscriber's features for one network may not be the same as the entity keeping keep track of his features in another network. For example, in the CS CN of cellular networks, an HLR is the aforementioned entity, whereas in an IMS CN, an AS may be the aforementioned entity, if it is not the HSS. It is important to keep disparate feature stores synchronized in scenarios where both types of CNs are deployed in parallel and where a subscriber subscribes to similar services. For example, if a subscriber in a GSM network activates call-forwarding service, he would expect that feature to be activated for him in a IMS network when accessing that same feature using the latter. And conversely, there is a need to for feature actions made in the IMS network to propagate to the HLR in the GSM network.
Depending on the service architecture and interfaces available, the IMS network may not be able to get subscriber supplementary service information directly from the HLR. Thus there is a need for a system in which cellular-based feature actions are propagated into IMS, without requiring that the HLR have a direct interface for subscriber information into IMS. Furthermore, there is also a need for feature actions, made in IMS, to propagate to the wireless HLR.